The cycle of disbanding that keep casuals from doing content

[Snugglebutt]

That's just about how it will be. Endgame requires a bit of dedication to it. Learning the mechanics, downing the fight after many attempts. If you're slow at learning, or incapable of dedicating the time to learn the ins and outs of the fight... You're pretty much out of luck. The skilled(and those with a lot of time) are rewarded, while those who lack those get left behind.

Second coil is not endgame, final coil is endgame for the time being while second coil is old content just like trial hard version vs extreme version. Second coil should of been added to to DF in 2.4 without a full pre-made group requirement when final coil came out but SE failed to make it so. They will probably do it in a later patch or expansion but they should of already done it the moment final coil came out.